Does look like there is still tissue there but a close up would help
@ashburn2k - how many frags have you thrown out when they look like that!?!
Did you dip to check for bugs or take an ICP? You might find a particular level is off. Some acros are more sensitive to certain things so just because others are doing ok doesn’t mean nothings wrong.
I wouldn’t give up all hope on it yet.
I’ve never heard of that but there are other products that will remove po4. I never used gfo. I used phosguard instead.
Most hose connections are brass. I’ve had one expensive hose that had aluminum connections. Almost all hardware (screws and bolts) have a zinc coating to give it some corrosion resistance. Tin can be in a lot of things (including screws and bolts).